Conventionally, a black pigment has been preferred to be bluish rather than reddish in hue, and in recent years, there is an increasing marketability for those capable of realizing a more vivid tone in a wide range of fields, leading to a strong desire for a black pigment that can realize a more vivid bluish hue. Under such circumstances, complex inorganic oxide black pigments are widely known over years as inorganic pigments excellent in heat resistance, flooding resistance, fastness and the like, and are extensively used as colorants in general paints led by heat-resistant paints and also as coloring materials for ceramics. The above-described complex inorganic oxide black pigments include Cu—Cr-based, Cu—Cr—Mn-based, Cu—Mn-based, Cu—Mn—Fe-based, Co—Cr—Fe-based, and like ones, and have a spinel structure in general. Their production processes can be roughly divided into two groups, one including dry processes that the oxides, carbonates or the like of individual constituent metals are mixed and baked and the resulting baked product is ground, and the other wet processes that soluble salts of individual constituent metals are dissolved into a solution of mixed salts, these salts are precipitated with an alkali or the like to obtain a precursor, and the precursor is baked.
In the production of a complex inorganic oxide black pigment, it is extremely difficult and in fact, impossible to obtain a pigment of small primary particles by a dry method. From such a background, the present applicant, together with its affiliated company, already conducted research in an attempt to obtain a pigment of small primary particles, and to date, have proposed black pigments produced by a wet method and having excellent tinting power, vividness and color developability and a production process thereof (Patent Document 1). However, the black pigments proposed in Patent Document 1 are hardly considered to be sufficient in the degree of bluishness to meet the high performance desired for the hue of a black pigment in recent years. Accordingly, the present applicant, together with its affiliated company, has made a further proposal on a production process of a black pigment, which optimizes the composition of the black pigment to provide it with a more bluish hue (Patent Document 2).